1. Field of the Invention
The present invention relates generally to mobile devices such as mobile phones and controlling techniques for mobile devices. In more detail, the invention relates to controlling techniques whereby a user controls a mobile device by moving it.
2. Description of the Related Art
Over the past few years a number of techniques have been developed to obtain and utilize motion information about a mobile device. One of these techniques is based on the use of accelerometers, when a mobile device is equipped with at least one accelerometer that continuously measures the motion of the mobile device. The mobile device estimates on the basis of the measurement results which way a user has tilted the mobile device. For example, the mobile device may calculate the difference in the tilt angle of the current position in comparison to the previous position of the mobile device. Thereafter a certain action is performed on the basis of the tilt angle. For example, if the mobile device presents menu options, the menu options can be scrolled forward or backward according to the tilt angle.
FIG. 1A shows a mobile phone presenting a menu before a tilt. We may assume that the mobile phone 101 is equipped with an accelerometer. The mobile phone 101 presents a menu 102 on its display 103 and said menu contains three options. The options are the names of people whom a user can call by selecting one of the options. At the moment the middle option 104 is highlighted, i.e. the user can select it, for example, by pressing a certain button.
FIG. 1B shows the mobile phone 101 presenting the menu 102 when the user has tilted it to a new position. In more detail, the user has tilted the mobile phone so that the upper edge 105 is now farther away from the user than in the FIG. 1A. The tilt angle from the position of the mobile phone shown in FIG. 1A to the new position is approximately −20 degrees 106. Because of the tilt, the upper option 107 of the menu 102 is now highlighted. Correspondingly, if the user tilts the mobile phone from the position shown in FIG. 1A to another new position so that the upper edge 105 of the mobile phone is closer to the user, the lower option 108 will be highlighted.
FIG. 1C shows the content of the menu 102 after a rapid tilt. The intensive tilt is not necessarily related to the magnitude of the tilt angle, but to how quickly the new position of the mobile phone is achieved. Now the menu options are scrolled so that the menu includes a new menu option 109. Thus, the menu 102 is scrolled forward. Correspondingly, if the user tilts the upper edge 105 of the mobile phone 101 rapidly closer to himself/herself, the menu is scrolled backward.
FIGS. 1B and 1C show examples of received motion information about a mobile device. The said motion information indicates “a longitudinal tilt” of the mobile device.
The motion information may also indicate that the user has tilted the right edge 108 of the mobile phone 101 either farther from himself/herself or closer to himself/herself. This is termed “a horizontal tilt”.
A mobile device can be adapted to detect the longitudinal and/or horizontal tilt of the mobile device and to then scroll longitudinally and/or horizontally the content shown on its display. This is a very useful feature, for example, when browsing web pages. The feature makes it possible to browse even large and complicated web pages with a relatively small-sized display.
In prior art, the motion information of a mobile/portable device can be obtained using one or more accelerometers. Accelerometers are relatively inexpensive and reliable. Alternatively, the said motion information can be obtained using inclinometers or gyroscopes. Also “optical navigation” can be used to control devices. Especially Agilent Technologies has developed the last-mentioned technique.
FIG. 2 shows a portable electronic device equipped with mouse-like capabilities. The device 201 includes a display 202 and a motion sensor 203. The display shows the same menu as in FIG. 1A and the middle option 204 is currently highlighted. When a user moves his/her finger 205 upwards 206, the upper option 207 is highlighted. The user must press the finger 205 against the motion sensor 203, or keep the finger very close to it, to be able to control the device 201. The operation of the optical navigation is in general based on sequential images received by the motion sensor and the comparative difference in luminance between the said images. The optical navigation and the motion sensor 203 are further described in EP1241616.
The prior art has certain drawbacks. Accelerometers and inclinometers are sensitive to vibration. Therefore a portable device equipped with an accelerometer or an inclinometer may be difficult to control inside of a moving car or when walking. Said device has also rather limited operating positions. Gyroscopes do not suffer from vibration, but they do suffer from so-called drift. In addition, gyroscopes are mechanically complicated and thus expensive devices.
Also the known implementations of optical navigation suffer from vibration. Another drawback with these implementations is that a user must use both hands, i.e. the user holds the mobile/portable device in one hand and controls said device with a finger of the other hand. For example, in the device 101 the display 103 is large-sized, almost covering the whole front surface of the device 101. If a motion sensor is plugged into the front surface of the device 101, the user's hand will at least partially cover the display.
Thus, the drawbacks related to the prior art optical navigation and mobile/portable devices are: 1) the user needs both hands for using a mobile/portable device and 2) the user's hand may partially cover the display of said device.